1. Field of the Invention
The present invention relates generally to sensor housing construction, and more particularly, to preformed sensor housings and methods to produce thin metal diaphragms.
2. Background of the Invention
Diaphragms and membranes are structures that play a critical role in pressure sensors. Diaphragms are used in pressure sensors such that pressure is usually measured by detecting and quantifying the deflection of a diaphragm onto which pressure is applied. Another important application of diaphragms is to isolate two different media from each other, but still allow transmission of pressure from one medium to another. This is normally done to protect a pressure-sensing element from an incompatible environment by encapsulating the sensor in a housing that is filled with a neutral fluid such as silicone oil. The external pressure is transmitted to the oil, and therefore to the pressure sensor, through a flexible membrane that is hermetically attached to the housing. In this application, the diaphragm also functions as an isolation membrane to “isolate” one environment from the other. When these diaphragms and isolation membranes are metallic, they may be attached to housings by various methods such as welding, brazing, or with the use of adhesives. These attachment methods, however, are difficult to implement when the application requires very small diaphragms or membranes (i.e., diaphragms and membranes having very small diameters, or sizes). An example of such applications is implantable medical catheters used to measure pressure inside the body.